1. Field
The present disclosure relates to polypeptide linkers, compositions or kits including the polypeptide linkers, and methods of analyzing a target material using the polypeptide linkers.
2. Description of the Related Art
Cancer metastasis is a process whereby malignant cells from a primary cancer region are transferred to tissues at a distance via blood. Circulating tumor cells (CTCs), which are rare tumor cells that are present in blood vessels and circulate the body, are known to be involved in cancer metastasis with respect to the primary cancer. Even in the case of patients with advanced metastasis, the amount of CTCs in the blood is very small and, thus, it is difficult to separate the CTCs efficiently.
In order to detect and separate cancer cells in a patient's body, cancer cell separation has been studied based on affinity or size of the cells. However, separation by affinity chromatography is so complicated that cancer cells may be lost or have an early detection limit. Also, CTC separation by size filtration may not isolate small cancer cells. In addition, cancer diagnosis does not only simply involve separation and cytometry of cancer cells, but also involves expansion of applications to provide clinically meaningful data for cell analysis, medical research, pharmaceutical research, and disease diagnosis by efficiently separating tumor cells in a biological sample. Based on analysis of proteins or genes of cancer cells, data for diagnosis and prescription is necessary for the purpose of treatment of cancer as well as pretreatment for detection and measurement.
However, an immunofluorescence-based protein assay, wherein proteins of cancer cells are separated by a polymer or a magnetic bead, causes fluorescent signal distortion due to the presence of the bead, so a bead removal step is necessary for reliable analysis. In order to separate the bead from the cancer cells, a method to remove either a binding of an antigen and antibody, or a linker therebetween, may be applied. A physical method, wherein changes in the pH of the solution containing cancer cells cause a decrease in the affinity of antibodies, may damage the cancer cells, and a chemical method performed by a compound is also unsuitable for the diagnosis using molecular analysis.
Therefore, there is still a demand for a method that may be performed without affecting the CTCs to analyze the CTC-surface proteins and intracellular genes.